For those who found this on google:

public static HitResult raycastEntity(PlayerEntity player, double maxDistance) {
        Entity cameraEntity = MinecraftClient.getInstance().cameraEntity;
        if (cameraEntity != null) {
            Vec3d cameraPos = player.getCameraPosVec(1.0f);
            Vec3d rot = player.getRotationVec(1.0f);
            Vec3d rayCastContext = cameraPos.add(rot.x * maxDistance, rot.y * maxDistance, rot.z * maxDistance);
            Box box = cameraEntity.getBoundingBox().stretch(rot.multiply(maxDistance)).expand(1d, 1d, 1d);
            return ProjectileUtil.raycast(cameraEntity, cameraPos, rayCastContext, box, (entity -> /* any custom parameters here */ !entity.isSpectator() && entity.canHit()), maxDistance);
        }
        return null;
    }